Epoxy compound, precursor thereof, production processes thereof, use of the precursor and cured product of the epoxy compound

ABSTRACT

There is provided a novolak-type hydroxycarboxylic acid or an ester thereof, an epoxy compound produced therefrom, a composite material comprising a matrix resin of the cured product and a reinforcing material, and a process for the production of the epoxy compound. The epoxy compound produces a cured product having excellent water resistance, heat resistance, chemical resistance, mechanical properties, dimensional stability and electrical properties.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to a novel epoxy compound, a precursor thereofand processes for the production thereof, and use of the precursor and acured product of the epoxy compound. More specifically, it relates to anepoxy cured product having excellent water resistance, heat resistance,chemical resistance, mechanical properties, dimensional stability andelectrical properties, an epoxy compound to provide the epoxy curedproduct, a precursor of the epoxy compound, production processes thereofand use of the precursor as an epoxy curing agent.

Conventionally, cured epoxy resins are widely used in fields of coatingcompositions, electrical insulating materials, civil engineering andconstruction materials, adhesives, fiber-incorporated reinforcedcomposite materials, and the like due to their various excellentproperties. And, the following processes are well known as a practicalprocess for the production of a heat-resistant cured epoxy resin amongthese cured epoxy resins used in such fields.

1. A process in which tetraglycidyl-methylene-dianiline anddiaminodiphenyl sulfone are reacted and cured.

2. A process in which a polyglycidyl ether of phenol novolak anddiaminodiphenylsulfone are reacted and cured.

3. A process in which tetraglycidyl-methylene-dianiline anddicyandiamide are reacted and cured, and

4. A process in which a polyglycidyl ether of phenol novolak anddicyandiamide are reacted and cured.

U.S. Pat. No. 4,394,496 discloses a monomeric epoxide of the formula##STR1## wherein Q is H or an alkyl group of from 1 to about 10 carbonatoms;

each R independently represents an alkyl group of from 1 to about 12carbon atoms, a phenyl or cycloalkyl group of from 3 to about 6 carbonatoms; and

each Z independently represents H or ##STR2## with the proviso that atleast one Z on each of Rings I, II and III is ##STR3## each Yindependently represents H or methyl; each X independently representsbromo, chloro or nitro;

each p independently is 0, 1 or 2,

each n independently is 0, 1 or 2, and the sum of n+p for each ringbeing 0, 1, 2 or 3 when both Z groups are other than hydrogen.

In the above epoxide, none of the Rings I, II and III do not contain anyoxygen-containing group other than the nitro and glycidyl ether groupsas is clear from the above definition.

Japanese Laid-Open Patent Publication No. 36205/1980 discloses a processfor the production of a high-purity epoxide (whose epoxy equivalent isabout 125 to 140) of the following formula, ##STR4## wherein Y is asdefined above, which comprises reacting p-hydroxy benzoic acid andepihalohydrin.

The above epoxide has its characteristic features in that it contains aglycidyl ester group in addition to a glycidyl ether group as anoxygen-containing group, as is shown in the above formula.

Said Japanese Laid-Open Patent Publication No. 36205/1980 discloses onlyusefulness of the above epoxide as a curing agent for a coatingcomposition powder, and discloses nothing concerning the performances ofthe cured product of the above epoxide. However, the present inventors'study has showed that the cured product of the above epoxide has veryhigh water absorption and when it is immersed in a boiling water, itswater resistance decreases with an increase in swelling. The reasontherefor is not clear. However, one major reason is believed to be thatsaid epoxide contains, in addition to a glycidyl ether group, a glycidylester group as the oxygen-containing hydrophilic groups in the molecule.

Therefore, it is an object of this invention to provide a novel epoxycompound.

It is another object of this invention to provide an epoxy compoundwhich has many oxygen-containing hydrophilic groups such as glycidylether and glycidyl ester groups but gives a cured product havingexcellent water resistance equivalent to that of a cured product of anepoxy compound having a corresponding skeleton structure free from anyglycidyl ester group.

It is further another object of this invention to provide an epoxycompound which gives a cured product having not only excellent waterresistance but also excellent heat resistance, chemical resistance,mechanical properties, dimensional stability and electrical properties.

It is still another object of this invention to provide a novelhydroxycarboxylic acid and an ester thereof as a precursor of the aboveepoxy compound.

It is yet another object of this invention to provide industriallyadvantageous processes for producing the above epoxy compound andprecursor of this invention efficiently and economically.

It is further another object of this invention to provide novel use ofthe above hydroxycarboxylic acid and ester thereof, provided by thisinvention, as an epoxy curing agent.

Further, it is another object of this invention to provide a curedproduct having the above-described excellent properties derived from theepoxy compound of this invention.

It is still further another object of this invention to provide acomposite material which comprises, as a matrix resin, a cured productderived from the epoxy compound of this invention and has excellentproperties.

Other objects and advantages of this invention will be apparent from thefollowing description.

According to this invention, the above objects and advantages of thisinvention are achieved by a compound of the following formula (II)##STR5## wherein: Ar¹, Ar² and Ar³ may be same or different and eachindependently represents a benzene skeleton, a naphthalene skeleton or askeleton of the formula ##STR6## in which X is a bond, --O--, --S--,--SO₂ --, ##STR7## or an alkylidene group having 1 to 3 carbon atoms,provided that these skeletons may be substituted with a halogen atom oran alkyl group having 1 to 5 carbon atoms and that the total number ofcarbon atoms of each of Ar¹, Ar² and Ar³ is not more than 20, ##STR8##R³ and R⁴ may be same or different and each independently represents##STR9## or an alkyl group having 1 to 10 carbon atoms, p is a number of0 to 20, and

r, s and t are independently a number of 1 to 3.

FIG. 1 shows an infrared absorption spectrum of a hydroxycarboxylic acidobtained in Example 1, (1).

FIG. 2 shows an infrared absorption spectrum of an epoxy compoundobtained in Example 1. (2).

FIG. 3 shows an NMR spectrum of an epoxy compound obtained in Example 1.(2).

FIG. 4 shows an NMR spectrum of a hydroxycarboxylic acid obtained inExample 2. (1).

FIG. 5 shows an NMR spectrum of an epoxy compound obtained in Example 2.(2).

FIG. 6 shows an NMR spectrum of a hydroxycarboxylic acid obtained inExample 3. (1).

FIG. 7 shows an infrared absorption spectrum of a hydroxycarboxylic acidobtained in Example 4.

In the formula (II), Ar¹, Ar² and Ar³ may be same or different and eachindependently represents a benzene skeleton, a naphthalene skeleton or askeleton of the formula ##STR10## in which X is a bond, --O--, --S--,--SO₂ --, ##STR11## or an an alkylidene group having 1 to 3 carbonatoms.

As is clear from the formula (II), Ar¹ bonds to (OG)_(r) and one CH, Ar³bonds to (OG)_(t) and one CH, and Ar² bonds to (OG)_(s) and two CH's.

It is therefore noted that when these Ar¹, Ar² and Ar³ have no othersubstituent except for OG and CH('s), Ar¹ represents a skeleton having avalence of (1+r), Ar³ shows a skeleton having a valence of (1+t) and Ar²shows a skeleton having a valence of (2+s). Similarly, it is also notedthat when these skeletons further have other substituent(s), thevalances thereof increase by a number equivalent to the valence of theother substituent(s). For example, when Ar¹ bonds to one OG group (r=1)and a CH group, Ar¹ represents a skeleton having a valance of 2, andwhen the Ar¹ is further substituted with one other substituent, the Ar¹represents a skeleton having a valence of 3.

Examples of the skeletons represented by Ar¹, Ar² and Ar³ are ##STR12##

As other substituent(s) substitutable on Ar¹, Ar² and Ar³, there arehalogen atoms and an alkyl group having 1 to 5 carbon atoms. Examples ofthe halogen atoms are fluorine, chlorine, bromine and iodine. The alkylgroup having 1 to 5 carbon atoms may be linear or branched, and examplesthereof are methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl,iso-butyl, tert-butyl and n-pentyl.

When the "other" substituent(s) is an alkyl group having 1 to 5 carbonatoms, the total number of carbon atoms of the skeleton including such asubstituent is twenty at maximum. For example, three n-pentyl groups(each having 5 carbon atoms) are substituted on a benzene skeleton(having 6 carbon atoms), the total number of carbon atoms of theskeleton including the substituents is twenty-one (21), and such a caseis therefore excluded from the scope of this invention.

That is, examples of the benzene and naphthalene skeletons representedby Ar¹, Ar² and Ar³ on which such "other" substituent(s) is substitutedare a monomethylbenzene skeleton, a dimethylbenzene skeleton, amonochlorobenzene skeleton, a dichlorobenzene skeleton, amonochloromonomethylbenzene skeleton, a monochloronaphthalene skeleton,a monobromobenzene skeleton, a dibromobenzene skeleton, tribromobenzeneskeleton, a tetrabromobenzene skeleton (only in the case of Ar¹ andAr³), and a monobromonaphthalene skeleton.

Preferred as Ar¹, Ar² and Ar³ are, for example, a benzene skeleton, amonomethylbenzene skeleton, a naphthalene skeleton, a monochlorobenzeneskeleton, a dichlorobenzene skeleton, a monobromobenzene skeleton and adibromobenzene skeleton. Particularly preferred among these are abenzene skeleton, a monomethylbenzene skeleton, a naphthalene skeletonand a dibromobenzene skeleton.

In the formula (II), ##STR13## R³ and R⁴ may be same or different andeach independently represents ##STR14## or an alkyl group having 1 to 10carbon atoms.

The alkyl group having 1 to 10 carbon atoms may be linear or branched,and examples thereof are methyl, ethyl, n-propyl, butyl, pentyl, hexyl,heptyl, octyl, nonyl and decyl groups.

Preferred as R³ and R⁴ are ##STR15## and methyl.

p is a number of 0 to 20, preferably of 0 to 5. When p exceeds 1, pluralAr² 's, plural R⁴ 's and plural G's may be respectively identical ordifferent.

r, s and t may be same or different and each independently represents anumber of 1 to 3. When r, s and t are numbers of not less than 2, pluralG's in each case may be identical or different.

In the formula (II), corresponding to the above preferred examples ofAr¹ and Ar³, specific examples of (OG)_(r) --Ar¹ -- and (OG)_(t) --Ar³-- are preferably monoglycidyloxyphenyl (G= ##STR16## r=1, Ar¹ =divalentbenzene skeleton), di(glycidyloxy)phenyl (G= ##STR17## r=2, Ar¹=trivalent benzene skeleton), monoglycidyloxymonomethylphenyl ##STR18##r=1, Ar¹ =trivalent benzene skeleton monosubstituted with a methylgroup), monoglycidyloxynaphthyl ##STR19## r=1, Ar¹ =divalent naphthaleneskeleton), monochloromonoglycidyloxyphenyl ##STR20## r=1, Ar¹ =trivalentbenzene skeleton monosubstituted with a chlorine atom),dichloromonoglycidyloxyphenyl (G= ##STR21## r=1, Ar¹ =tetravalentbenzene skeleton disubstituted with chlorine atoms),monobromomonoglycidyloxyphenyl ##STR22## r=1, Ar¹ =trivalent benzeneskeleton monosubstituted with a bromine atom), anddibromomonoglycidyloxyphenyl (G= ##STR23## r=1, Ar¹ =tetravalent benzeneskeleton disubstituted with bromine atoms).

Similarly, corresponding to the above preferred examples of Ar²,specific examples of (OG)_(s) --Ar² < are preferablymonoglycidyloxyphenylene ##STR24## s=1, Ar³ =trivalent benzeneskeleton), di(glycidyloxy)phenylene ##STR25## s=1, Ar² =tetravalentbenzene skeleton), monoglycidyloxymonomethylphenylene ##STR26## s=1, Ar²=tetravalent benzene skeleton monosubstituted with a methyl group),monoglycidyloxynaphthylene ##STR27## s=1, Ar² =trivarent naphthaleneskeleton), monochloromonoglycidyloxy-phenylene ##STR28## s=1, Ar²=tetravalent benzene skeleton monosubstituted with a chlorine atom),dichloromonoglycidyloxyphenylene ##STR29## s=1, Ar² =pentavalent benzeneskeleton substituted with disubstituted with chlorine atoms),monobromomonoglycidyloxyphenylene ##STR30## s=1, Ar² =tetravalentbenzene skeleton monosubstituted with a bromine atom), anddibromomonoglycidyloxyphenylene ##STR31## s=1, Ar² =pentavalent benzeneskeleton disubstituted with bromine atoms).

It is believed that specific examples of the compound of the formula(II) are clear on the basis of the above explanation. Some of suchexamples are as follows. ##STR32##

According to this invention, the above epoxy compound of this inventionis produced by a process which comprises reacting a compound selectedfrom the group consisting of hydroxycarboxylic acids and esters thereofof the following formula (I) ##STR33## wherein Ar¹, Ar² and Ar³ are asdefined in the formula (II), R¹ and R² may be same or different and eachindependently represents a hydrogen atom or an alkyl group having 1 to10 carbon atoms, q is a number of 0 to 20, and l, m and n are a numberof 1 to 3, with a halohydrin selected from epihalohydrins andβ-methylepihalohydrins,

(i) at one step in the presence of a basic compound, or

(ii) first in the presence of a quaternary ammonium salt and then in thepresence of a basic compound.

The compound of the above formula (I) is novel. Therefore, thisinvention proposes the compound of the formula (I) as well as thecompound of the formula (II).

It is to be noted that the explanation of the definition of Ar¹, Ar² andAr³ in the formula (II) can be applied to the definition of Ar¹, Ar² andAr³ in the formula (I) as well.

In the formula (I), R¹ and R² may be same or different and eachindependently represents a hydrogen atom or an alkyl group having 1 to10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atomsare the same as those specified with regard to the formula (II).Preferred as R¹ and R² are a hydrogen atom and a methyl group.

q is a number of 0 to 20, preferably of 0 to 5. When q exceeds 1, pluralAr² 's and plural R² 's may be respectively identical or different. l, mand n may be same or different and each independently represents anumber of 1 to 3.

In the above formula (I), specific examples of (OH)_(l) --Ar¹ and(OH)_(n) --Ar³ -- are preferably monohydroxyphenyl (l=1, Ar¹ =divalentbenzene skeleton), dihydroxyphenyl (l=2, Ar¹ =trivalent benzeneskeleton), monohydroxymonomethylphenyl (l=1, Ar¹ =trivalent benzeneskeleton monosubstituted with a methyl group), monohydroxynaphthyl (l=1,Ar¹ =divalent naphthalene skeleton), monochloromonohydroxyphenyl (l=1,Ar¹ =trivalent benzene skeleton monosubstituted with a chlorine atom),dichloromonohydroxyphenyl (l=1, Ar¹ =tetravalent benzene skeletondisubstituted with chlorine atoms), monobromomonohydroxyphenyl (l=1, Ar¹=trivalent benzene skeleton monosubstituted with a bromine atom), anddibromomonohydroxyphenyl (l=1, Ar¹ =tetravalent benzene skeletondisubstituted with bromine atoms).

Similarly, examples of (OH)_(m) Ar² <are preferably monohydroxyphenylene(m=1, Ar² =trivalent benzene skeleton), dihydroxyphenylene (m=2, Ar²=tetravalent benzene ring), monohydroxymonomethylphenylene (m=1, Ar²=tetravalent benzene skeleton monosubstituted with a methyl group),monohydroxynaphthylene (m=1, Ar² =trivalent naphthalene skeleton),monochloromonohydroxyphenylen (m=1, Ar² =tetravalent benzene skeletonmonosubstituted with a chlorine atom), dichloromonohydroxyphenylene(m=1, Ar² =pentavalent benzene skeleton disubstituted with chlorineatoms), monobromomonohydroxyphenylene (m=1, Ar² =tetravalent benzeneskeleton monosubstituted with a bromine atom) anddibromomonohydroxyphenylene (m=1, Ar² =pentavalent benzene skeletondisubstituted with bromine atoms).

It is believed that specific examples of the compound of the formula (I)are clear on the basis of the above explanation. Some of such examplesare as follows. ##STR34##

The compound of the formula (I) is a hydroxycarboxylic acid when R¹ andR² are hydrogen atoms, and it is a hydroxycarboxylate ester when atleast one of R¹ and R² is an alkyl group.

In the above process of this invention, the compound of the formula (I)and a halohydrin are reacted with each other as described above.

As a halohydrin, any one of epihalohydrins and β-methylepihalohydrins isusable.

Examples of the halohydrin are preferably epichlorohydrin,epibromohydrin, β-methylepichlorohydrin, and β-methylepibromohydrin. Ofthese, epichlorohydrin and β-methylepichlorohydrin are particularlypreferred. These halohydrins may be used alone or in combination. Theamount of the halohydrin for use is usually at least 2 mols, preferablyat least 3 mols, particularly preferably at least 5 mols, based on oneequivalent weight of hydroxyl and carboxyl groups, in total, of thecompound of the formula (I).

The hydroxycarboxylic acid or its ester of the formula (I) and thehalohydrin are reacted

(i) at one step in the presence of a basic compound, or

(ii) first in the presence of a quaternary ammonium salt and then in thepresence of a basic compound.

Examples of the basic compound for use in the above process (i) arepreferably alkali metals such as sodium and potassium, hydroxidesthereof, carbonates thereof and bicarbonates thereof. Above all, sodiumhydroxide is particularly preferred.

The amount of such a basic compound for use based on one equivalentweight of hydroxyl and carboxyl groups, in total, of the compound of theformula (I) in total is usually at least 0.8 equivalent weight,preferably 0.9 to 3.5 equivalent weight, particularly preferably 1 to 3equivalent weight.

The reaction above is carried out usually at a temperature between 30°C. and 150° C., preferably between 50° C. and 130° C., particularlypreferably between 60° C. and 120° C. The reaction time is usually 1 to20 hours.

In the above process (ii), the reaction is carried out first in thepresence of a quaternary ammonium salt.

Examples of the quaternary ammonium salt are preferably tetraalkyl- orbenzyltrialkylammonium salts such as tetramethylammonium chloride,tetraethylammonium chloride, benzyltrimethylammonium chloride andbenzyltrimethylammonium acetate. The amount of the quaternary ammoniumsalt for use based on one equivalent weight of hydroxyl and carboxylgroups, in total, of the compound of the formula (I) is preferably 0.001to 0.1 mol. For the reaction temperature and reaction time in this case,those conditions specified concerning the above process (i) can be alsoemployed.

After the reaction at the first step, a basic compound is added to thereaction system to carry out the reaction at the second step. Theabove-specified basic compound at this second step. For the reactiontemperature and reaction time at this second step, those conditionsspecified concerning the above process (i) can be also employed.

The reaction product obtained in the above process (i) or (ii) isusually subjected to post treatment in which unreacted epihalohydrin orβ-methylepihalohydrin is removed from the reaction mixture bydistillation, and optionally, the remainder is dissolved in a solventincompatible with water such as toluene, benzene, or the like and then awater-soluble inorganic substance is removed by extraction with water orby filtration.

The epoxy compound of the formula (II) can be produced as describedabove according to this invention. The resultant epoxy compound isoptionally dissolved in an organic solvent such as methyl butyl ketone,benzene or toluene, and further subjected to heat treatment in thepresence of a basic compound, e.g. at a temperature between 60° C. and100° C. for 1 to 20 hours. The amount of the basic compound for use inthis treatment is preferably not more than 0.6 equivalent weight,particularly preferably 0.2 to 0.5 equivalent weight, based on oneequivalent weight of hydroxyl and carboxyl groups, in total, of thecompound of the formula (I). Thus, the epoxy compound can be obtained asa product whose halogen content as impurities is further reduced.

The novel compound of the formula (I) which is used as a startingmaterial in the process of this invention and which also constitutespart of this invention can be produced in the following processaccording to this invention. This process also constitutes part of thisinvention.

That is, the compound of the formula (I) can be produced by a processwhich comprises subjecting to a dehydration and condensation reaction analdehyde compound of the formula (III) ##STR35## wherein R^(o) is ahydrogen atom or an alkyl group having 1 to 10 carbon atoms and anaromatic hydroxy compound of the formula (IV)

    Ar.sup.o --(OH).sub.u                                      (IV)

wherein Ar^(o) is a benzene skeleton, a naphthalene skeleton or askeleton of the formula ##STR36## in which X is a bond, --O--, --S--,--SO₂, ##STR37## or an alkylidene group having 1 to 3 carbon atoms,provided that these skeletons may be substituted with a halogen atom oran alkyl group having 1 to 5 carbon atoms and that the total number ofcarbons of Ar^(o) is not more than 20, and

u is a number of 1 to 3,

in the presence of an acidic catalyst, and optionally, then subjectingthe reaction product to a hydrolysis reaction.

In the formula (III), R^(o) is a hydrogen atom or an alkyl group having1 to 10 carbon atoms.

Examples of the alkyl group having 1 to 10 carbon atoms are the same asthose specified concerning R³ and R⁴ in the formula (II). Preferred asR^(o) are a hydrogen atom and methyl, ethyl and propyl groups.

Examples of the aldehyde compound of the formula (III) are preferablyp-formylbenzoic acid, methyl p-formylbenzoate, ethyl p-formylbenzoateand propyl p-formylbenzoate. Of these, p-formylbenzoic acid and methylp-formylbenzoate are particularly preferred.

The above aldehyde compounds may be used alone or in combination.

The aromatic hydroxy compound, as the other starting material, which isreacted with the above aldehyde compound is represented by the aboveformula (IV).

In the formula (IV), Ar^(o) is a benzene skeleton, a naphthaleneskeleton or a skeleton of the following formula ##STR38##

In the above formula, X is a bond, --O--, --S--, --SO₂, ##STR39## or analkylidene group having 1 to 3 carbon atoms. And, these skeletons may besubstituted with a halogen atom or an alkyl group having 1 to 5 carbonatoms, provided that the total number of carbons of Ar^(o) is not morethan 20.

The explanation of the definition of Ar¹, Ar² and Ar³ in the formula(II) can be applied to the definition of the above Ar^(o) as well. u isa number of 1 to 3.

Examples of the aromatic hydroxy compound of the formula (IV) aremonohydroxyphenolic compounds (u=1) such as phenol, cresol, xylenol,α-naphthol, β-naphthol, bromophenol, chlorophenol, dibromophenol,dichlorophenol, tribromophenol and trichlorophenol; dihydroxyphenoliccompounds (u=2) such as resorcinol, dihydroxynaphthalene,bromoresorcinol, chlororesorcinol, dibromoresorcinol,dichlororesorcinol, tribromoresorcinol and trichlororesorcinol; andtrihydroxyphenolic compounds (u=3) such as trihydroxybenzene.

Of these compounds, preferred are phenol, cresol, α-naphthol,β-naphthol, bromophenol, 2,6-dibromophenol and resorcinol.

The above aromatic hydroxy compounds may be used alone or incombination.

The aldehyde compound and the aromatic hydroxy compound are subjected toa dehydration and condensation reaction in the presence of an acidiccatalyst.

The aldehyde compound and the aromatic hydroxy compound are usually usedin such a ratio that the amount of the aromatic hydroxy compound is 0.5to 2 mole per mole of the aldehyde compound. This ratio can be suitablyvaried depending upon the polymerization degree q of an intendedcompound, ie. the compound of the formula (I).

Examples of the acidic catalyst are protonic acids such as nitric acid,sulfuric acid, hydrochloric acid, phosphoric acid, methanesulfonic acid,toluenesulfonic acid and oxalic acid; and Lewis acids such as borontrifluoride, boron trifluoride ether complex, aluminum chloride, tinchloride, zinc chloride, iron chloride and titanium chloride.

Of these, protonic acids are preferred, and in particular, hydrochloricacid, boric acid, methanesulfonic acid and toluenesulfonic acid arepreferred.

The amount of the acidic catalyst for use is preferably 0.001 to 0.05mol per mole of the aldehyde compound. The above acidic catalysts may beused alone or in combination.

The reaction is preferably carried out at a temperature between 80° C.and 250° C. Further, the reaction is advantageously carried out bysetting the reaction temperature between 80° C. and 150° C. at theinitial stage and gradually increasing the reaction temperature to adesired range.

The reaction time is 1 to 24 hours.

A reaction solvent may be used for the reaction, and an excess amount ofthe aromatic hydroxy compound may be optionally used so that thearomatic hydroxy compound itself can function as a reaction solvent.Examples of the reaction solvent are preferably aromatic hydrocarbonssuch as toluene, chlorobenzene, dichlorobenzene, nitrobenzene anddiphenyl ether; and ethers such as ethylene glycol dimethyl ether anddiethylene glycol dimethyl ether.

According to the above process, in the case of use of an aldehydecompound of the formula (III) in which R^(o) is a hydrogen atom, thereis obtained a hydroxycarboxylic acid of the formula (I) in which R¹ andR² are hydrogen atoms.

Further, in the case of use of an aldehyde compound of the formula (III)in which R^(o) is an alkyl group having 1 to 10 carbon atoms, there isobtained an ester of a hydroxycarboxylic acid of the formula (I) inwhich R¹ and R² are corresponding alkyl groups of a hydroxycarboxylateester in which part of the ester groups are converted to carboxyl groupsunder hydrolysis.

Such an ester may be optionally subjected to a hydrolysis reactionaccording to the process of this invention, whereby a hydroxycarboxylicacid formed by converting the ester group to a carboxyl group can beobtained. The hydrolysis can be carried out according to a known methodoptionally in the presence of an acid or alkali.

As is clear from the above explanation, according to this invention,there is provided a process for the production of the epoxy compound ofthis invention, which comprises producing the hydroxycarboxylic acid orits ester of the formula (I) from the aldehyde compound of the formula(III) and the aromatic hydroxy compound of the formula (IV), and furtherreacting the reaction product with a halohydrin.

The present inventors have further made a study of such a process ofthis invention and succeeded in development of an industriallyadvantageous production process, which is also proposed here as aprocess of this invention.

That is, the above-mentioned process of this invention comprises thefollowing three steps:

(1) a step of subjecting an aldehyde compound of the formula (III)-1##STR40## wherein R^(o1) is an alkyl group having 1 to 10 carbon atoms,and an aromatic hydroxy compound of the formula (IV) to a hydration andcondensation reaction in the presence of an acidic catalyst,

(2) a step of subjecting the resultant reaction mixture to a hydrolysisreaction in the presence of a basic compound, and

(3) a step of adding a halohydrin selected from epihalohydrins andβ-methylepihalohydrins to the resultant hydrolysis reaction mixture toreact a hydrolysis reaction product in said mixture with the halohydrin.

The aldehyde compound of the formula (III)-1 to be used in the step (1)corresponds to the aldehyde compound of the formula (III) in which R^(o)is an alkyl group having 1 to 10 carbon atoms.

The aromatic hydroxy compound of the formula (IV) is also usable as theother starting material.

For the acidic catalyst and the dehydration reaction conditions, theremay be employed the same acidic catalysts and conditions as those in theabove process for the production of the hydroxycarboxylic acid and anester thereof.

Then, in the step (2), the reaction mixture obtained in the step (1) issubjected to a hydrolysis reaction in the presence of a basic compoundwithout isolating a formed hydroxycarboxylate ester from said reactionmixture.

For the basic compound and the amount thereof for use, there may beemployed the same basic compounds and amounts as those specified withregard to the variant (i) of the present process for the production ofthe epoxy compound of this invention.

The hydrolysis reaction is carried out at a temperature preferablybetween 30° C. and 150° C., more preferably between 50° C. and 130° C.,particularly preferably between 60° C. and 120° C. The hydrolysisreaction time is about 20 minutes to about 20 hours.

In addition, it is advantageous to remove an unreacted aldehyde compoundand aromatic hydroxy compound from the reaction mixture obtained in thestep (i) prior to performance of the step (2), for example, bydistillation under reduced pressure and to preliminarily add a basiccompound in order to deactivate the acidic catalyst.

Further, in the step (3), a halohydrin is added to the hydrolysisreaction mixture obtained in the step (2) without isolating the formedhydroxycarboxylic acid from said hydrolysis reaction mixture, thereby toreact the hydrolysis reaction product with the halohydrin.

Examples of the halohydrin are the same as those specified concerningthe process for the production of the epoxy compound of this invention.The amount of the halohydrin for use is preferably at least 2 mols, morepreferably at least 3 mols, particularly preferably 5 mols, based on oneequivalent weight of carboxyl and hydroxyl groups, in total, of thehydroxycarboxylic acid fully expected to be present in the hydrolysisreaction mixture. The reaction is usually carried out at a temperaturebetween 30° C. and 150° C., preferably at a temperature between 40° C.and 130° C., particularly preferably at a temperature between 50° C. and120° C.

The reaction time varies depending on a reaction temperature and astirring state, and is usually 1 to 48 hours. The reaction system is aheterogeneous system formed of a water phase and a halohydrin phase, andit is therefore advantageous to carry out the reaction in the presenceof a phase transfer catalyst such as quaternary ammonium salt or a crownether.

The epoxy compound can be isolated from the so-formed reaction mixturein the same way as in the foregoing process of this invention for theproduction of the epoxy compound of this invention.

Furthermore, the present inventors have found that the hydroxycarboxylicacid or its ester of the formula (I) can be also used as a curing agentfor an epoxy compound in addition to use of as a starting material forthe production of the epoxy compound of the formula (II) provided bythis invention.

That is, the epoxy curing agent of this invention comprises thehydroxycarboxylic acid or its ester of the formula (I).

The preferably epoxy compound for which the epoxy curing agent of thisinvention is advantageously usable is a polyepoxy compound having atleast two epoxy groups in the molecule, and examples thereof are asfollows.

1) Glycidyl ether-type compounds

Aromatic polyols such as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A),4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylsulfone,resorcinol, phenol novolak, cresol novolak, resorcinol novolak, naphtholnovolak, dihydroxynaphthalene novolak; polyols obtained by a dehydrationreaction between an aromatic hydroxy compound such as phenol,dihydroxybenzene, naphthol, dihydroxynaphthalene, or the like and analdehyde such as glyoxal, glutaraldehyde, p-hydroxybenzaldehyde,benzaldehyde, or the like, e.g. in the presence of an acidic catalyst;glycidyl ethers of polyols such as polyhydric alcohols, i.e. butanediol,polypropylene glycol, polyethylene glycol, glycerol, etc., and precursorpolymers thereof.

2) Glycidyl ester-type compounds

Glycidyl esters of dicarboxylic acids such as phthalic acid, isophthalicacid, tetrahydrophthalic acid, naphthalenedicarboxylic acid, etc., andprecursor polymers thereof.

3) N-Glycidyl-type compounds

Compounds formed by substituting a glycidyl group for active hydrogenbonded to a nitrogen atom of nitrogen-containing compounds such asaniline, isocyanuric acid, methylenedianiline, etc.

4) Glycidyl ether ester-type compounds

Glycidyl ether esters of hydroxycarboxylic acids such asp-hydroxybenzoic acid, hydroxynaphthoic acid, etc.

5) Others

Epoxy resins obtained from alicyclic compounds such as cyclopentadiene,dicyclopentadiene, etc., a triglycidyl compound of p-aminophenol,vinylcyclohexenedioxide, etc.

Of the above polyepoxy compounds, preferred in view of availability andheat resistance of a thermosetting resin to be formed are diglycidylether of 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), diglycidyl etherof 4,4'-dihydroxydiphenylmethane, polyglycidyl ether of phenol novolak,polyglycidyl ether of naphthol novolak, polyglycidyl ether of a polyolobtained by a dehydration reaction between phenol and glyoxal,glutaraldehyde, benzaldehyde or p-hydroxybenzaldehyde in the presence ofan acidic catalyst, diglycidyl ether of polypropylene glycol, diglycidylether of polyethylene glycol, diglycidyl ether of butanediol, diglycidylether of glycerol, triglycidyl ether of glycerol,N,N,N',N'-tetraglycidylmethylenedianiline, diglycidyl ether ester ofp-hydroxybenzoic acid, diglycidyl ether ester of 2-hydroxy-6-naphthoicacid, a triglycidyl compound of p-aminophenol and vinylcyclohexenedioxide. Particularly preferred are diglycidyl ether of bisphenol A,polyglycidyl ether of phenol novolak, polyglycidyl ether of α-naphtholnovolak, polyglycidyl ether of a polyol obtained by a dehydrationreaction between phenol and glyoxal, glutaraldehyde, benzaldehyde orp-hydroxybenzaldehyde in the presence of an acidic catalyst, diglycidylether of polypropylene glycol, diglycidyl ether of polyethylene glycol,diglycidyl ether of butanediol, diglycidyl ether of glycerol,triglycidyl ether of glycerol,N,N,N',N'-tetraglycidylmethylenedianiline, a triglycidyl compound ofp-aminophenol and vinylcyclohexenedioxide. These compounds may be usedalone or in combination.

A resin composition comprising the epoxy curing agent of this inventionmay, as required, additionally contain another curing agent, a curepromoter, a filler, etc. In particular, the cure promoter can furtherimproves the low-temperature curability of the composition to a greatextent when it is incorporated into the curing agent of this inventionimmediately before use. Examples of the cure promoter are preferablytertiary amines such as N,N-dimethylbenzylamine,α-methylbenzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol andhexamethoxymethylmelamine; amine oxides such as N,N-dimethylbenzylamineoxide, phosphorus compounds such as triphenylphosphine; boron aminecomplexes such as BF₃ -piperidine and triethanolamine borate; boric acidester derivative, and aniline-formaldehyde resin. Particularly preferredare tertiary amines such as N,N-dimethylbenzylamine,α-methylbenzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol andphosphorus compounds such as triphenylphosphine. The amount of the curepromoter for use is 0.05 to 5% by weight, preferably 0.1 to 1% byweight, particularly preferably 0.2 to 0.8% by weight, based on theepoxy resin composition. Advantageously, the polyepoxy compound, theepoxy curing agent of this invention and optionally, the above curepromoter are mixed, and a curing reaction is carried out while theresultant mixture is shaped directly or through a so-called B-stageresin in which the mixture partly undergoes the reaction.

The above curing agent may be partially replaced with other curingagent, e.g. polyphenols such as phenol novolak, cresol novolak orpolyvinyl phenol, and an anhydrous curing agent such as trimelliticanhydride or phthalic anhydride.

The above epoxy resin composition may further contain a suitable amountof other additive depending upon required functions of a cured product,and examples thereof are inorganic powders such as an alumina powder andwollastonite; a powder of a metal such as aluminum, copper or silver, adyestuff, a pigment, etc.

The resin mixture before being cured may be formed into a powder orflake form and transfer-molded or compression-molded.

Further, the resin mixture may be used as a coating composition or anadhesive by coating a substrate surface with it in a form of a solutionsuch as a varnish, and drying and curing the resultant coating.

Furthermore, such a varnish may be used to form a composite material byimpregnating it into a reinforcing material such as a glass fiber, aglass fabric, a carbon fiber, an aramide fiber, etc., to prepare aso-called prepreg, and press-molding or autoclave-molding the prepreg.

The epoxy resin cured product according to this invention has low watervapor absorption and excellent electrical properties and heatresistance, and it can therefore be suitably used in fields of advancedtechnologies such as an electronic and electric field including asemiconductor sealing agent, aerospace industry, and the like.

The epoxy compound of the formula (II), provided by this invention, canbe cured with a conventional epoxy curing agent and can be formed into acured epoxy resin having excellent heat resistance.

Examples of such a curing agent are amines, ananhydride, a polyamideresin, a polysulfide resin, a boron trifluoride amine complex, a novolakresin, a dicyandiamide, etc.

Specific examples of the above curing agent are (a) aliphatic aminessuch as diethylenetriamine, triethylenetetramine,1,3-diaminocyclohexane, isophoronediamine and xylylenediamine; andaromatic amines such as m-phenylenediamine, p-phenylenediamine,4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone,3,3'-diaminodiphenylsulfone, 2,4-toluylenediamine, 4,4'-diaminodiphenylether, 3,4'-diaminodiphenyl ether and an aniline-formalin resin; (b) anadduct of the above aliphatic or aromatic amine with a monoepoxycompound (ethylene oxide, phenylglycidyl ether, butylglycidyl ether, orthe like), a polyepoxy compound (diglycidyl ether of bisphenol A,diglycidyl ether of resorcin, or the like), acrylonitrile, or the like;(c) anhydrides such as phthalic anhydride, hexahydrophthalic anhydride,Nadic anhydride, methyl Nadic anhydride, pyromellitic anhydride,benzophenonetetracarboxylic anhydride, trimellitic anhydride, glycerintristrimellitate, and ethylene glycol trimellitate; (d) a polyamideresin of a dimer acid with diethylenetetramine, triethylenetetramine, orthe like; (e) a polysulfide resin having a mercaptan group at each end;(f) a complex of an amine such as aniline, N-methylaniline, benzylamine,ethylamine or the like with boron trifluoride; (g) a low molecularweight novolak resin obtained from phenol, cresol and formalin; and (h)dicyandiamide.

The novel epoxy compound of this invention can be cured with aconventional curing agent for epoxy resin as described above. Inparticular, it exhibits an excellent effect in use requiring heatresistance when it is cured with an aromatic polyamine and/ordicyandiamide.

Of the above curing agents, 4,4'-diaminodiphenylsulfone anddicyandiamide are particularly preferred.

Concerning the above curing agents, the amines, the polyamide resin, thepolysulfide resin, the boron trifluoride amine complex, the novolakresin, etc., are used such that the ratio of the amount of activehydrogen of these curing agents/the epoxy equivalent of the epoxycompound is 0.5 to 1.5 by mole, preferably 0.8 to 1.2 by mole. Theanhydride is used such that the ratio of its anhydride group amount/theepoxy equivalent of the epoxy compound is 0.5 to 1.0 by mole, preferably0.6 to 0.9 by mole. The dicyandiamide is used such that the ratio of itsactive hydrogen amount/the epoxy equivalent of the epoxy compound is1/20 to 1/3 by mole, preferably 1/10 to 1/4 by mole.

The novel epoxy compound of this invention is cured together with theabove epoxy curing agent to form a heat-resistant cured resin.

In this case, the above-described conventional polyepoxy compounds suchas a glycidyl ether compound, glycidyl ester compound, N-glycidylcompound and a glycidyl ether ester compound may be used in combinationwith the epoxy compound of this invention, and a small proportion of acure promoter may be incorporated.

Examples of the cure promoter are tertiary amines such as triethylamine,tributylamine and dimethylbenzylamine; phenols such as phenol, cresol,butylphenol, nonylphenol, chlorophenol, resorcinol and polyvinylphenol;imidazoles such as imidazole, 2-ethyl-4-methylimidazole; and salts suchas acetates of these.

The amount of the cure promoter for use is preferably 0.05 to 5% byweight, more preferably 0.1 to 1% by weight, particularly preferably 0.2to 0.8% by weight, based on the thermosetting resin comprising the epoxycompound.

The epoxy compound of this invention can be directly cured by adding thecuring agent, etc., thereto, as described above. Alternatively, theepoxy compound may dissolved in a solvent, and a curing agent and,optionally, a cure promoter are homogeneously dispersed or dissolved inthe mixture, followed by removing the solvent to obtain a homogeneousmixture and curing it. Examples of such a solvent are ketones such asacetone, methyl ethyl ketone, methyl butyl ketone and diethyl ketone;alcohols such as methyl cellosolve and ethyl cellosolve; cyclic etherssuch as dioxane and tetrahydrofuran; amides such as dimethylformamide,dimethylacetamide and N-methylpyrrolidone; and aromatic hydrocarbonssuch as benzene, toluene, xylene and and cumene.

The above thermosetting resin can be formed into a cured product bysubjecting it to a curing reacation at a time of molding directly orthrough a so-called B-stage resin in which part of the resin hasreacted.

The curing reaction of the epoxy compound of this invention can proceedat a temperature of 40° C. or higher, and it is carried out under heatpreferably at a temperature between 70° C. and 250° C.

The cure time is usually 0.5 to 5 hours. The cured product has furtherimproved heat resistance when it is post-cured preferably at atemperature of 150° C. or higher.

According to this invention, there is provided a cured product of athermosetting resin comprising the epoxy compound of the formula (II)provided by this invention, and there is further provided a curedproduct of a thermosetting resin mainly comprising the epoxy compound ofthe formula (II) provided by this invention.

Further, according to this invention, there is provided a compositematerial comprising a matrix resin of a cured product of a thermosettingresin comprising the epoxy compound of the formula (II) provided by thisinvention and a reinforcing material such as a carbon fiber, an aramidefiber or a glass fiber, as described above.

The above cured molded article and composite material of this inventionare excellent in water resistance, heat resistance, chemical resistance,mechanical properties, dimensional stability and electrical properties,and are suitably usable in advanced technology fields such as anelectronic and electric field including a semiconductor sealing agent,an aerospace industry field, etc.

Further, according to another aspect of this invention, there areprovided:

a hydroxycarboxylic acid or its ester, which corresponds to a compoundformed by substituting at least part of the following formula ##STR41##in the formula (I) with a certain special group, and

an epoxy compound which corresponds to a compound formed by substitutingat least part of the following formula ##STR42## in the formula (II)with a certain special group.

Such a hydroxycarboxylic acid or an ester thereof and such an epoxycompound are usable completely in the same way as the hydroxycarboxylicacid or its ester of the formula (I) and the epoxy compound of theformula (II).

Such a hydroxycarboxylic acid or an ester thereof has the followingformula (I)': ##STR43## wherein Ar¹, Ar², Ar³, l, m, n and q are asdefined in the formula (I), and X¹ and X² may be same or different andare independently a group selected from the class consisting of##STR44## in which R⁵ is a hydrogen atom or an alkyl group having 1 to10 carbon atoms, R⁶ is --OH or --NH₂, and R⁷ and R⁸ may be same ordifferent and each independently represents a hydrogen atom or an alkylgroup having 1 to 10 carbon atoms, provided that at least 15 mol %,preferably at least 20 mol %, particularly preferably at least 25 mol %of each of the X¹ and X² is the group of the following formula ##STR45##

The hydroxycarboxylic acid or its ester of the formula (I)' can beproduced according to the process for the production of the compound ofthe formula (I) except that part of the aldehyde of the formula (III) isreplaced with a compound of the formula (III)' and/or a compound of theformula (III)", for example, p-hydroxybenzaldehyde [compound of theformula (III)'] and/or formaldehyde or acetaldehyde [compound of theformula (III)"] ##STR46## The epoxy compound corresponding to theformula (I)' has the following formula (II)'. ##STR47## wherein Ar¹,Ar², Ar³, G, r, s, t and p are as defined in the formula (II), and X¹and X² are as defined in the formula (I)'.

The epoxy compound of the formula (II)' can be produced according to theprocess for the production of the epoxy compound of the formula (II)except that the hydroxycarboxylic acid or its ester of the formula (I)is replaced with the compound of the formula (I)'.

It is believed that specific examples of the compounds of the formulae(I)' and (II)' are self-evident on the basis of the specific examples ofthe compounds of the formula (I) and (II) and the definitions of X¹ andX².

As specified hereinabove, there are provided a cured product and acomposite material which have excellent water resistance, heatresistance, mechanical properties, dimensional stability and electricalproperties, and there are also provided a novel epoxy compound and aprecursor thereof which give such a cured product and such a compositematerial. Further, according to this invention, these epoxy compound andprecursor can be produced efficiently and economically. Therefore, thisinvention produces industrially and practically various effects inaddition to these advantages.

This invention will be explained hereinbelow by reference to Examples,which, however, shall not limit this invention.

In Examples, "part" stands for "part by weight" unless otherwisespecified.

Infrared absorption spectrum analysis (IR) and nuclear magneticresonance spectrum analysis (NMR) used for identifying epoxy compoundsobtained in Examples are as follows.

a) Infrared absorption spectrum analysis (IR)

A neat epoxy compound was casted on a KBr plate and measured forinfrared absorption spectrum according to a conventional method.

b) Neuclear magnetic resonance spectrum analysis (NMR):

The measurement was made by using d-chloroform as a solvent andtetramethylsilane as a reference.

EXAMPLE 1

(1) 235 Parts of phenol, 25 parts of p-formylbenzoic acid, 0.05 part ofp-toluenesulfonic acid onohydrate and 0.07 part of concentratedhydrochloric acid were allowed to react under nitrogen atmosphere at 60°C. for 3 hours with stirring, and then allowed to react for 12 hourswith gradually elevating the temperature of the reaction mixture so thatthe reaction temperature finally reached 160° C. During the reaction,water formed as a result of the reaction was distilled out of thereaction system. The resultant reaction product was taken out of thereactor, 300 parts of toluene was added, and the resultant mixture waswashed with 100 parts of water three times. Then, unreacted phenol wasdistilled off at 80° C. under reduced pressure of 5 mmHg, and furtherremoved by flushing the mixture with steam to give 30 parts of ahydroxycarboxylic acid.

The hydroxycarboxylic acid had a melting point of 130° to 145° C. and amolecular weight, measured by a cryoscopic method using dioxane, of 325.Elemental analysis thereof showed C(%): 75.35, H(%): 5.14.

IR spectrum of the above hydroxycarboxylic acid was shown in FIG. 1, inwhich a broad peak assigned to hydroxyl groups and carboxyl groups isobserved at 3,000 to 3,600 cm⁻¹ and a peak assigned to carboxyl groupsis observed at 1,690 cm⁻¹.

These data shows that the above hydroxycarboxylic acid had the followingchemical structure. ##STR48## (wherein n≈0)

(2) 11 Parts of the above hydroxycarboxylic acid was added to 46 partsof epichlorohydrin and dissolved therein by heating the mixture to 80°C. 0.7 Part of a 60% aqueous solution of tetraethylammonium chloride wasadded dropwise over 2 hours, the resultant mixture was held at saidtemperature for 1 hour, and then 8 g of a 50% aqueous solution of sodiumhydroxide was added dropwise over 1 hour. And, the reaction was furthercontinued for 3 hours. After the reaction, epichlorohydrin was recoveredby distillation under reduced pressure, and 130 parts of toluene wasadded to the remainder. The resultant mixture was washed with 50 partsof water, with 50 parts of an aqueous solution of dilute phosphoric acidand further with 50 parts of water five time each to remove an excessamount of sodium hydroxide and precipitated sodium chloride. Toluene wasdistilled off from the toluene phase to give 14 parts of an epoxycompound having an epoxy equivalent of 208 g/eq and a melting point ofnot higher than 25° C., which had the following chemical structure. Theepoxy compound had a molecular weight, measured by a cryoscopic methodusing dioxane, of 508.

IR and NMR spectra of this epoxy compound are shown in FIGS. 2 and 3. InFIG. 2, a peak assigned to carboxyl groups is observed at 1,720 cm⁻¹,and a peak assigned to epoxy groups is observed at 910 cm⁻¹. In FIG. 3,peaks are observed at 2.2 to 4.8 ppm (m, 5H's of glycidyl group), at 5.2to 6.2 ppm (m, H of methyne group) and at 6.5 to 8.2 ppm (m, H ofaromatic ring). ##STR49## (wherein n≈0, and ##STR50##

EXAMPLE 2

(1) 1,410 Parts of phenol, 164 parts of methyl p-formylbenzoate, 1.5parts of p-toluenesulfonic acid monohydrate and 0.4 part of concentratedhydrochloric acid were allowed to react under nitrogen atmosphere at150° C. for 1 hour with stirring, and then allowed to react for 8 hourswith gradually elevating the temperature of the reaction mixture so thatthe reaction temperature finally reached 161° C. During the reaction,water formed as a result of the reaction was distilled out of thereaction system. The resultant reaction product was taken out of thereactor, 2,000 parts of toluene was added, and the resultant mixture waswashed with 600 parts of water three times. Then, toluene was distilledoff under reduced pressure, and unreacted phenol was distilled off at80° C. under reduced pressure of 5 mmHg, and further removed by flushingthe mixture with steam to give 311 parts of a hydroxycarboxylic acidderivative.

NMR spectrum of the resultant product is shown in FIG. 4, in which peaksare observed at 3.8 ppm (s, H of methyl ester), at 5.5 to 6.2 ppm (m, Hof methyne), at 6.5 to 8.2 ppm (m, H of aromatic ring) and at 9.2 to 9.5ppm (m, H of hydroxyl group). This NMR chart shows that 65% of thehydroxycarboxylic acid derivative obtained above was methyl ester.

The hydroxycarboxylic acid derivative had a melting of 115° to 130° C.and a molecular weight, measured by a cryoscopic method using dioxane,of 332. Elemental analysis thereof showed C(%): 75.35, H(%): 5.19.

These data shows that the above hydroxycarboxylic acid derivative hadthe following chemical structure. ##STR51## (wherein n≈0, 1/3 of R═H,2/3 of R═--CH₃)

(2) 214 Parts of the above hydroxycarboxylic acid derivative and 4.4parts of benzyltrimethylammonium chloride were added to 4,500 parts ofepichlorohydrin, and the resultant mixture was allowed to react at 80°C. for 5 hours while it was stirred.

After the temperature of the reaction mixture was adjusted to 95° C.,194 parts of a 50% aqueous solution of sodium hydroxide was addeddropwise over 1.5 hours at 160 mmHg with stirring. In this case, waterformed in the system was distilled out of the system. The resultantreaction mixture was purified in the same way as in Example 1 to give244 parts of an epoxy compound having an epoxy equivalent of 223 g/eq, amolecular weight, measured by a cryoscopic method using dioxane, of 402and a melting point of not higher than 25° C., and having the followingchemical formula. NMR spectrum of this epoxy compound is shown in FIG.5, in which a peak is observed at 3.8 ppm (H of methyl ester) inaddition to those peaks observed in FIG. 4. NMR showed that 65% of theepoxy compound was methyl ester. ##STR52## (wherein N≈0, ##STR53## 1/3of R═G, 2/3 of R═--CH₃)

EXAMPLE 3

(1) 1,500 Parts of a 5% aqueous solution of sodium hydroxide was addedto 160 parts of the hydroxycarboxylic acid derivative obtained inExample 2, and the mixture was refluxed under heat for 2 hours tohydrolyze the methyl ester. Then, the hydrolysis product was subjectedto acidolysis with a 10% aqueous solution of hydrochloric acid, and theresultant solid was washed with 1,000 parts of water three times anddried at 80° C. under reduced pressure to give 123 parts of ahydroxycarboxylic acid. NMR (FIG. 6) showed that the resultanthydroxycarboxylic acid was completely hydrolyzed. That is, the peak (Hof methyl ester) at 3.8 ppm observed in FIG. 4 is not observed in FIG.6.

The above hydroxycarboxylic acid had a melting point of 133° to 146° C.,and a molecular weight, measured by a cryoscopic method using dioxane,of 329. Elemental analysis showed C(%): 75.37, H(%): 5.15.

IR spectrum of this compound is greatly similar to that of the compoundobtained in Example 1.(1), and it was found that the compound obtainedin this Example had the structural formula shown in Example 1.(1).

(2) The above hydroxycarboxylic acid was subjected to glycidylation inthe same way as in Example 2 to give 200 parts of an epoxy compoundhaving an epoxy equivalent of 196 g/eq and a melting point of not higherthan 25° C. This epoxy compound had a molecular weight, measured by acryoscopic method using dioxane, of 502. IR and NMR of this compoundwere nearly similar to those in FIGS. 2 and 3.

EXAMPLE 4

1,410 Parts of phenol, 164 parts of ethyl p-formylbenzoate, 1.5 parts ofp-toluenesulfonic acid monohydrate and 0.4 part of concentratedhydrochloric acid were allowed to react under nitrogen atmosphere at150° C. for 1 hour with stirring, and then allowed to react for 8 hourswith gradually elevating the temperature of the reaction mixture so thatthe reaction temperature finally reached 161° C. During the reaction,water formed as a result of the reaction was distilled out of thereaction system. Then, unreacted phenol was distilled off from thereaction mixture at 80° C. under reduced pressure of 5 mmHg, and furtherremoved by flushing the mixture with steam. 2,000 Parts of a 10% aqueoussolution of sodium hydroxide was added to the resultant compound, andthe mixture was refluxed under heat for 2 hours, and then subjected toacidolysis with a 10% aqueous solution of hydrochloric acid. Theresultant solid was washed with 1,000 parts of water three times anddried under reduced pressure at 80° C.

The resultant hydroxycarboxylic acid had a melting point of 148° to 195°C. and a molecular weight, measured by a cryoscopic method usingdioxane, of 587. Elemental analysis showed C(%): 73.98, H(%): 4.01.

IR spectrum of this compound is shown in FIG. 7, in which, similarly tothose in FIG. 1, a broad peak assigned to a hydroxyl group and acarboxyl group is observed at 3,000 to 3,600 cm⁻¹ and a peak assigned tocarbonyl of a carboxyl group is observed at 1,690 cm⁻¹.

These data showed that the above hydroxycarboxylic acid had thefollowing chemical structure. ##STR54## (wherein mean value of n=1.2).

EXAMPLE 5 AND COMPARATIVE EXAMPLES 1 AND 2

20 Parts of the epoxy compound synthesized in Example 1 and4,4'-diaminodiphenylsulfone were mixed such that the amount of the epoxygroup of the epoxy compound and that of the active hydrogen atom of4,4'-diaminodiphenylsulfone became equimolar, and heated to form ahomogeneous solution. Immediately thereafter, the solution was chargedinto a mold heated to 220° C. to carry out a curing reaction for 1 hour.The resultant molded piece was cured at 220° C. for 4 hours, and thenmeasured for a glass transition temperature by a DMA (model 1090,supplied by du Pont) at a rate of temperature rise of 10° C./minute.

For comparison, a diglycidyl ether of bisphenol A (epoxy equivalent 190g/eq) and a polyglycidyl ether of phenol novolak (epoxy equivalent 178g/eq) were cured with 4,4'-diaminodiphenylsulfone in the same way asabove (Example 5), and the resultant resins were measured for a glasstransition temperature.

Table 1 shows the results.

                  TABLE 1                                                         ______________________________________                                                              Glass transition                                                  Epoxy compound                                                                            temperature (°C.)                                ______________________________________                                        Example 5   Synthesized in                                                                              304                                                             Example 1                                                         Comparative Diglycidyl ether                                                                            238                                                 Example 1   of bisphenol A                                                    Comparative Polyglycidyl ether                                                                          266                                                 Example 2   of phenol novolak                                                 ______________________________________                                    

The results shown in Table 1 show that the cured product of the epoxycompound of this invention has excellent heat resistance over those ofconventional compounds.

EXAMPLE 6

19.6 Parts of the epoxy compound synthesized in Example 1 and 2 parts ofdicyandiamide were heated to form a homogeneous solution, andimmediately thereafter, the solution was charged into a mold heated to200° C. to carry out a curing reaction for 1 hour.

The resultant molded piece was cured at 220° C. for 5 hours, andmeasured for a glass transition temperature in the same way as inExample 5.

The resultant cured product had a glass transition temperature of 290°C. and excellent heat resistance.

EXAMPLE 7 AND COMPARATIVE EXAMPLE 3

20 Parts of the epoxy compound obtained in Example 3 was dissolved in 30parts of acetone, and 4,4'-diaminodiphenylsulfone was added such thatthe amount of the epoxy group of the epoxy compound and that of theactive hydrogen atom of the 4,4'-diaminodiphenylsulfone became equimolarto form a homogeneous solution. And, the homogeneous solution wasformed, and acetone was evaporated at 80° C. Then, the solution wassubjected to a curing reaction in a press molding machine according to aconventional method under a pressure of 10 kg/cm³ at 200° C. for 1 hourto give a molded piece having a thickness of 3 mm, a width of 6 mm and alength of 120 mm. This molded piece was cured at 220° C. for 4 hours,and then measured for a glass transition temperature by a DMA (model1090, supplied by du Pont) at a rate of temperature rise of 10°C./minute.

For comparison, 6.2 parts of 4,4'-diaminodiphenylsulfone and 17.5 partsof a diglycidyl ether of bisphenol A (epoxy equivalent 175 g/eq) wereadded to 30 parts of acetone, and a resin was obtained by the sameprocedure as above (Example 7). The resulting resin was measured for aglass transition temperature. The results are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                              Glass transition                                                  Epoxy compound                                                                            temperature (°C.)                                ______________________________________                                        Example 7   Synthesized in                                                                              309                                                             Example 3                                                         Comparative Diglycidyl ether                                                                            242                                                 Example 3   of bisphenol A                                                    ______________________________________                                    

The results in Table 2 show that the cured product of the epoxy compoundof this invention has excellent heat resistance over that of aconventional compound.

EXAMPLES 8-11

(1) A phenolic compound of which the name and amount are shown in Table3 and 0.3 part of p-toluenesulfonic acid monohydrate were dissolved in90 parts of toluene, and the mixture was heated to form a solutionhaving a temperature of 100° C. And, a solution of 92 parts of methylp-formylbenzoate in 92 parts of toluene was added dropwise to the abovesolution over 2 hours under nitrogen atmosphere with stirring.

While water formed during the reaction was distilled out of the system,the reaction was further continued for 1 hour, and the resultantreaction mixture was further allowed to react at 110° C. for 1 hour. 3Parts of concentrated hydrochloric acid was added, and the resultantmixture was allowed to react for 1 hour, and further allowed to react at120° C. for 3 hours. 700 Parts of a 10% aqueous solution of sodiumhydroxide was added to the resultant reaction mixture, the mixture washydrolyzed under reflux by heating for 2 hours, a toluene phase was thenremoved, and a water phase was acidolyzed with a 10% aqueous solution ofhydrochloric acid aqueous solution to give a solid. The solid was washedwith 300 parts of water three times, and then an unreacted phenoliccompound was removed by distillation under reduced pressure and flushingwith steam to give a hydroxycarboxylic acid. Table 3 shows yields,melting points, molecular weights measured by a cryoscopic method usingdioxane, elemental analysis results and the structures of the resultinghydroxycarboxylic acids identified by IR and NMR.

                                      TABLE 3                                     __________________________________________________________________________    Phenolic                  Elemental                                           compound       Melting    analysis                                            ( ) = amount                                                                             Yield                                                                             point                                                                              Molecular                                                                           (%)                                                 (part)     (part)                                                                            (°C.)                                                                       weight                                                                              C  H  Structure                                     __________________________________________________________________________    Ex. 8                                                                             Resorcinol                                                                           184 149-161                                                                            402   68.19                                                                            4.40                                                                             mean value                                        (182)                       of q in                                                                       formula (I) = 0.2                             Ex. 9                                                                             Cresol 165 143-159                                                                            372   75.71                                                                            5.60                                                                             mean value                                        (178)                       of q in                                                                       formula (I) = 0.1                              Ex. 10                                                                           α-naphthol                                                                     167 149-162                                                                            428   78.9                                                                             4.70                                                                             mean value                                        (162)                       of q in                                                                       formula (I) = 0                                Ex. 11                                                                           Bisphenol A                                                                          231 153-179                                                                            580   77.50                                                                            6.05                                                                             mean value                                        (256)                       of q in                                                                       formula (I) = 0                               __________________________________________________________________________

(2) 100 Parts of the hydroxycarboxylic acid obtained above and 2 partsof benzyltrimethylammonium chloride were added to 2,000 parts ofepichlorohydrin, and the resultant mixture was allowed to react underreflux by heating with stirring for 5 hours. The reaction mixture wasadjusted to 95° C., and 100 parts of a 50% aqueous solution of sodiumhydroxide was added dropwise at 160 mmHg with stirring over 1.5 hours.In this case, water formed in the system was distilled off. Theresultant reaction mixture was purified in the same way as in Example1.(1). Table 4 shows yields, melting points, epoxy equivalents,elemental analysis results and structures of the epoxy compoundsidentified by IR and NMR.

                  TABLE 4                                                         ______________________________________                                                           Epoxy   Elemental                                                    Melting  equiva- analysis                                           Yield     point    lent    (%)                                                (part)    (°C.)                                                                           (g/eq)  C    H    Structure                                ______________________________________                                        Ex. 8 121     35-43    148   66.50                                                                              5.60 mean value                                                                    of p in formula                                                               (II) = 0.2                             Ex. 9 103     not      190   71.1 6.08 mean value                                           higher                   of p in formula                                      than 35                  (II) = 0.1                              Ex. 10                                                                             101      85-102  212   75.39                                                                              5.40 mean value                                                                    of p in formula                                                               (II) = 0                                Ex. 11                                                                             105      91-115  198   73.19                                                                              6.37 mean value                                                                    of p in formula                                                               (II) = 0                               ______________________________________                                    

EXAMPLE 12

100 Parts of the hydroxycarboxylic acid obtained in Example 1.(1) and 3parts of benzyltriethylammonium chloride were added to 2,200 parts ofβ-methylepichlorohydrin, and the resultant mixture was allowed to reactunder reflux by heating with stirring for 5 hours. The reaction mixturewas adjusted to 95° C., and 100 parts of a 50% aqueous solution ofsodium hydroxide was added dropwise at 160 mmHg with stirring over 1.5hours. In this case, water formed in the system was distilled off. Theresultant reaction mixture was purified in the same way as in Example1.(2) to yield 121 parts of an epoxy compound. The epoxy compound had amelting point of not higher than 35° C. and an epoxy equivalent of 202g/eq, and elemental analysis thereof showed C(%); 72.40, H(%); 6.40. Itsstructure identified by NMR and IR is as follows. ##STR55##

EXAMPLE 13

632 Parts of phenol, 4 parts of hydrochloric acid and 1.2 parts ofp-toluenesulfonic acid monohydrate were preliminarily heated in an oilbath at 100° C. Then, a homogeneous solution of 368 parts of methylp-formylbenzoate in 368 parts of toluene at 40° C. was added dropwiseover 2 hours under nitrogen atmosphere with stirring. The resultantmixture was allowed to react for 1 hour, and the bath temperature waselevated to 110° C. to continue the reaction further for 1 hour.Thereafter, 12 parts of concentrated hydrochloric acid was added and thereaction was further continued for 1 hour. The bath temperature waselevated to 140° C. and the reaction was further continued for 1.5hours. In this case, water formed as a result of the reaction wasdistilled out of the system. 5 Parts of a 50% aqueous solution of sodiumhydroxide was added to the resultant reaction mixture, and the mixturewas stirred for 15 minutes. Then, toluene and unreacted phenol weredistilled off under reduced pressure. 3,000 Parts of a 10% aqueoussolution of sodium hydroxide was added to the reaction mixture, and themixture was allowed to react for 5 hours under reflux by heating.

The resultant hydrolysis product was cooled to 70° C., 4,500 parts ofepichlorohydrin was added, and the resultant mixture was allowed toreact for 5 hours with stirring under nitrogen atmosphere.Epichlorohydrin was separated with a separating funnel, and theremainder was washed with 1,000 parts of water, with 1,000 parts of anaqueous solution of dilute phosphoric acid, and further with water fivetimes to remove an excess amount of the sodium hydroxide andprecipitated sodium chloride. Then, epichlorohydrin was distilled offunder reduced pressure, and phenylglycidyl ether partly formed as aby-product was distilled off under reduced pressure at 150° C. to give821 parts of an epoxy compound of the following formula, which had anepoxy equivalent of 210 g/eq and a melting point of not higher than 40°C. This epoxy compound had a molecular weight, measured by a cryoscopicmethod using dioxane, of 524. ##STR56##

EXAMPLE 14

4,4'-Diaminodiphenylsulfone was added to 30 parts of the epoxy compoundobtained in Example 1.(2) such that the amount of the epoxy group andthe amount of active hydrogen atom of the 4,4'-diaminodiphenylsulfonebecame equimolar. The resultant mixture was heated to 150° C. to form ahomogeneous solution. 0.23 Part of a trifluoroboran-monoethylaminecomplex was added to and homogeneously dissolved in the solution, andthe resultant solution was allowed to undergo a curing reaction at 180°C. for 5 hours.

The resultant molded plate was measured for a heat distortiontemperature with a HDT and VSP tester supplied by Toyo Seiki Seisakusho(this measurement method was also used in Examples hereinafter) to show281° C. It was thus found to have excellent heat resistance.

EXAMPLE 15

4,4'-Diaminodiphenylmethane was added to 100 parts of the epoxy compoundobtained in Example 1.(2) such that the amount of the epoxy group andthe amount of active hydrogen atom of the 4,4'-diaminodiphenylmethanebecame equimolar. The resultant mixture was heated to 150° C. to form ahomogeneous solution, and allowed to undergo a curing reaction in a moldpreliminarily heated to 180° C. for 1 hour. The resultant molded platewas cured at 200° C. for 2 hours and at 220° C. for 2 hours, and then,the cured plate was measured for a heat distortion temperature to show256° C. It was thus found to have excellent heat resistance.

EXAMPLE 16

(1) 86.1 Parts of the epoxy compound obtained in Example 1.(2) and 63.9parts of methyl Nadic anhydride (liquid) were heated to 100° C. to forma homogeneous solution. 1.5 Parts of benzyldimethylamine was added toand homogeneously mixed with this solution, and the resultant mixturewas subjected to a curing reaction for 1 hour in a mold preliminarilyheated to 150° C. The resultant molded plate was cured at 175° C. for 2hours, at 220° C. for 2 hours and further at 250° C. for 6 hours.

The resultant molded plate was measured for a heat distortiontemperature to show 270° C., and it was thus found to have excellentheat resistance.

(2) 100 Parts of the epoxy compound obtained in Example 1.(2) and 50parts of phenol novolak having a molecular weight of 350 were mutuallydissolved at 120° C. to form a homogeneous solution. And, 2 parts oftriphenylphosphine was added to and dissolved in the solution. Theresultant mixture was subjected to a curing reaction in a moldpreliminarily heated to 180° C. for 1 hour. The resultant molded platewas cured at 200° C. for 5 hours. The resultant molded plate wasmeasured for a heat distortion temperature to show 204° C., and it wasthus found to have excellent heat resistance.

EXAMPLE 17

80 Parts of the epoxy compound obtained in Example 1.(2), 20 parts ofdiglycidyl ether of bisphenol A having an epoxy equivalent of 178 g/eqand 4,4'-diaminodiphenylsulfone were mutually dissolved such that theamount of the epoxy group and the amount of active hydrogen atom of the4,4'-diaminodiphenylsulfone became equimolar. The resultant mixture washeated to 150° C. to form a homogeneous solution, and allowed to undergoa curing reaction in a mold preliminarily heated to 200° C. for 1 hour.The resultant molded plate was cured at 220° C. for 5 hours and at 230°C. for 2 hours, and the cured plate was measured for a heat distortiontemperature to show 269° C. It was thus found to have excellent heatresistance.

EXAMPLE 18

80 Parts of the epoxy compound obtained in Example 1.(2), 20 parts of aphenol novolak type epoxy having an epoxy equivalent of 178 g/eq and4,4'-diaminodiphenylsulfone were mutually dissolved such that the amountof the epoxy group and the amount of active hydrogen atom of the4,4'-diaminodiphenylsulfone became equimolar. The resultant mixture washeated to 150° C. to form a homogeneous solution, and allowed to undergoa curing reaction in a mold preliminarily heated to 200° C. for 1 hour.The resultant molded plate was cured at 220° C. for 5 hours and at 230°C. for 2 hours, and the cured plate was measured for a heat distortiontemperature to show 275° C. It was thus found to have excellent heatresistance.

EXAMPLE 19 AND COMPARATIVE EXAMPLE 4

30 Parts of the epoxy compound obtained in Example 1.(2) and4,4'-diaminodiphenylsulfone were mutually dissolved such that the amountof the epoxy group and the amount of active hydrogen atom of the4,4'-diaminodiphenylsulfone became equimolar. The resultant mixture washeated to 150° C. to form a homogeneous solution, and allowed to undergoa curing reaction in a mold preliminarily heated to 200° C. for 1 hour.The resultant molded plate was cured at 220° C. for 5 hours and at 230°C. for 2 hours.

The cured plate was measured for flexural properties according to ASTMD790. Table 5 shows the results.

For comparison, the above procedure was repeated except thattetraglycidylmethylenedianiline was used in place of the epoxy compound,and the Table 5 also show the results.

Table 5 shows that the cured product of this invention has excellentflexural properties at a high temperature over a conventional curedproduct.

                  TABLE 5                                                         ______________________________________                                                        Measure-   Flexural                                                           ment tem-  properties                                         Epoxy           perature   (kg/mm.sup.2)                                      compound        (°C.)                                                                             Strength Modulus                                   ______________________________________                                        Ex. 19  Epoxy       230        7.8    246                                             compound of 250        6.7    225                                             Example 1. (2)                                                                            270        4.8    187                                     C Ex. 4 Tetraglycidyl-                                                                            230        5.9    174                                             methylene-  250        3.1    119                                             dianiline   270        0.4     13                                     ______________________________________                                    

EXAMPLE 20 AND COMPARATIVE EXAMPLE 5

30 Parts of the epoxy compound obtained in Example 1. (2) and4,4'-diaminodiphenylsulfone were mutually dissolved such that the amountof the epoxy group and the amount of active hydrogen atom of the4,4'-diaminodiphenylsulfone became equimolar. The resultant mixture washeated to 150° C. to form a homogeneous solution, and allowed to undergoa curing reaction in a mold preliminarily heated to 200° C. for 1 hour.The resultant molded plate was cured at 220° C. for 5 hours and at 230°C. for 2 hours.

The resultant molded plate was cut into test piece having a size of 10mm×50 mm×3 mm, and the test piece was immersed in boiling water for 10days so that the water absorption determined by the following equationwas reached saturation, i.e. 5.4%. ##EQU1##

For comparison, the above procedure was repeated except thattetraglycidylmethylenedianiline or a glycidyl ether glycidylesterification product of p-hydroxybenzoic acid was used in place of theabove epoxy compound. The resultant test piece formed from thetetraglycidylmethylenedianiline had a water absorption of 6.6%, and theresultant test piece formed from the glycidyl ether glycidylesterification product of p-hydroxybenzoic acid caused swelling duringthe treatment in boiling water.

These results show that the a molded article formed from the epoxycompound of this invention had better water absorption although theepoxy compound of this invention contains a glycidyl ester bond.

EXAMPLE 21 AND COMPARATIVE EXAMPLE 6

900 Parts of the epoxy compound obtained in Example 1. (2) and4,4'-diaminodiphenylsulfone were homogeneously dissolved in 750 parts ofacetone such that the amount of the epoxy group and the amount of activehydrogen atom of the 4,4'-diaminodiphenylsulfone became equimolar,whereby a resin solution for immersion was prepared.

A carbon fiber (3,000 filaments (1,800 De), Torayca T 400, supplied byToray Industries Inc.) was immersed in the above resin solution forimpregnation, and taken up around a drum having a width of 31.5 cm suchthat 323 filaments of the fiber were unidirectionally and uniformlywound on the drum widthwise. Then, the wound drum was heat-treated in adryer at 65° C. for 45 minutes while acetone was removed. After the heattreatment, the winding filaments were cut in one place to giveplate-like prepregs having a width of 31.5 cm.

17 Sheets of the prepregs obtained above were laminated such that thefilaments' directions were uniform, and the laminate was allowed toundergo a curing reaction with a press-molding machine under pressure of60 kg/cm² at 180° C. for 40 minutes to give a molded article having athickness of 3 mm, a width of 315 mm and a length of 315 mm. This moldedarticle was cured at 220° C. for 5 hours and 230° C. for 2 hours, andthe cured article was measured for flexural properties according to ASTMD-970. Table 6 shows the results.

For comparison, the above procedure and measurement were repeated exceptthat tetraglycidylmethylenedianiline was used in place of the epoxycompound. Table 6 also shows the results.

Table 6 shows that the molded article formed from the epoxy compound ofthis invention has excellent flexural properties at a high temperatureover that formed from a conventional compound.

                  TABLE 6                                                         ______________________________________                                                        Measure-   Flexural                                                           ment tem-  properties                                         Epoxy           perature   (kg/mm.sup.2)                                      compound        (°C.)                                                                             Strength Modulus                                   ______________________________________                                        Ex. 21  Epoxy       230        83     11,000                                          compound of 250        71     10,600                                          Example 1. (2)                                                                            270        58     10,100                                  C Ex. 6 Tetraglycidyl-                                                                            230        61      9,400                                          methylene-  250        32      5,300                                          dianiline   270        18      3,600                                  ______________________________________                                    

EXAMPLE 22 AND COMPARATIVE EXAMPLE 7

The molded plates prepared in Examples 21 and Comparative Example 6 wereimmersed in boiling water for 10 days, and the plates were measured forflexural properties. Table 7 shows the results. The results of Table 7show that the molded plate formed from the epoxy compound of thisinvention has excellent flexural properties under humidity and heat overthat formed from a conventional compound.

                  TABLE 7                                                         ______________________________________                                                        Measure-   Flexural                                                           ment tem-  properties                                         Epoxy           perature   (kg/mm.sup.2)                                      compound        (°C.)                                                                             Strength Modulus                                   ______________________________________                                        Ex. 22  Epoxy       150        93     12,800                                          compound of 200        69     12,000                                          Example 1. (2)                                                                            230        51     10,500                                  C Ex. 7 Tetraglycidyl-                                                                            150        80     11,300                                          methylene-  200        33      6,000                                          dianiline   230        24      5,200                                  ______________________________________                                    

EXAMPLE 23

1.5 Parts of p-toluenesulfonic acid monohydrate was dissolved in 603parts of phenol, and the resultant mixture was heated to 100° C. to forma solution. A solution of 164 parts of p-formylbenzoic acid in 164 partsof toluene was added dropwise to the above solution over 2 hours undernitrogen atmosphere with stirring. While water formed during thereaction was distilled out of the system, the mixture was furtherallowed to react for 1 hour, and the reaction mixture was furtherallowed to react at 110° C. for 2 hours and at 120° C. for 3 hours.

1,250 Parts of a 10% aqueous solution of sodium hydroxide was added tothe resultant reaction mixture, and the resultant mixture was subjectedto hydrolysis under reflux by heating. Then, a toluene phase wasseparated off, and a water phase was acidolyzed with a 10% aqueoussolution of hydrochloric acid. The resultant solid was dissolved in1,500 parts of methyl isobutyl ketone, washed with 600 parts of waterthree times, and then methyl isobutyl ketone and phenol were distilledoff under reduced pressure to give 295 parts of a polyhydroxycarboxylicacid.

The above polyhydroxycarboxylic acid had a melting point of 130° to 145°C. and a molecular weight, measured by a cryoscopic method usingdioxane, of 415. Elemental analysis thereof showed C(%); 74.87, H(%);4.92.

IR and NMR analysis of the above hydroxycarboxylic acid showed that ithad the following chemical structure. ##STR57## (wherein n≈0.4)

EXAMPLES 24 AND 25 AND COMPARATIVE EXAMPLE 8

100 Parts of an epoxy resin (a phenol novolak type epoxy having an epoxyequivalent of 179 g/eq) and 50 parts of the polyhydroxycarboxylic acidprepared in Example 1. (1) or 23 as a curing agent were charged into atest tube, and homogeneously mixed with each other at 120° C. Then, 2parts of triphenylphosphine as a cure promoter was added, andhomogeneously mixed with the mixture in the test tube. The resultantmixture was charged into a mold preliminarily heated to 180° C. to allowthe mixture to react for 1 hour. The cured product was taken out, andsubjected to post-cure treatment at 180° C. for 5 hours.

Table 8 shows heat distortion temperatures (HDT) of cured productsobtained above.

For comparison, the procedure of Examples 24 and 25 was repeated exceptthat phenol formalin novolak having a molecular weight of 504 was usedin place of the polyhydroxycarboxylic acid, and the resultant curedproduct was measured for a heat distortion temperature. Table 8 alsoshows the result.

                  TABLE 8                                                         ______________________________________                                                  Curing agent  HDT (°C.)                                      ______________________________________                                        Example 24  Polyhydroxycarboxylic                                                                         145                                                           acid prepared in                                                              Example 1. (1)                                                    Example 25  Polyhydroxycarboxylic                                                                         151                                                           acid prepared in                                                              Example 23                                                        Comparative Phenol formalin 132                                               Example 8   novolak                                                           ______________________________________                                    

EXAMPLES 26 AND 27 AND COMPARATIVE EXAMPLE 9

2 Parts of an epoxy resin (a phenol novolak type epoxy having an epoxyequivalent of 179 g/eq) and 1.2 parts of the polyhydroxycarboxylic acidprepared in Example 1. (1) or 23 as a curing agent were charged into atest tube, and homogeneously mixed with each other at 120° C. Then, 0.04part of triphenylphosphine as a cure promoter was added andhomogeneously mixed with the mixture in the test tube. The test tube wasimmersed in an oil bath at 180° C. to measure the temperature of theresin solution in the test tube.

Table 9 shows times required for reaching a maximum exothermictemperature from the bath temperature (180° C.) (maximum exothermictemperature attainable time).

For comparison, the above procedure and measurement were repeated exceptthat the same phenol formalin novolak as that used in ComparativeExample 8 was used in place of the above polyhydroxycarboxylic acidprepared in Example 26 or 27. Table 9 also shows the result.

It was found that the use of the polyhydroxycarboxylic acid of thisinvention makes the reaction faster.

                  TABLE 9                                                         ______________________________________                                                             Maximum exothermic                                                            temperature attain-                                             Curing agent  able time (sec.)                                         ______________________________________                                        Example 26                                                                             Polyhydroxycarboxylic                                                                         14                                                            acid prepared in                                                              Example 1. (1)                                                       Example 27                                                                             Polyhydroxycarboxylic                                                                         11                                                            acid prepared in                                                              Example 23                                                           Comparative                                                                            Phenol formalin 25                                                   Example 9                                                                              novolak                                                              ______________________________________                                    

What is claimed is:
 1. A compound selected from a hydroxycarboxylic acidor its ester of the formula (I) ##STR58## wherein: Ar¹, Ar² and Ar³ maybe same or different and each independently represents a benzeneskeleton, a naphthalene skeleton or a skeleton of the formula ##STR59##in which X is a bond, --O--, --S--, --SO₂ --, ##STR60## or an alkylidenegroup having 1 to 3 carbon atoms, provided that these skeletons may besubstituted with a halogen atom or an alkyl group having 1 to 5 carbonatoms and that the total number of carbon atoms of each of Ar¹, Ar² andAr³ is not more than 20,R¹ and R² may be same or different and eachindependently represents a hydrogen atom or an alkyl group having 1 to10 carbon atoms, q is a number of 0 to 20, and each of l, m and n is anumber of 1 to
 3. 2. A compound according to claim 1, wherein the (OH)--Ar¹ -- and (OH)_(n) --Ar³ -- of the formula (I) may be same ordifferent and are independently selected from the group consisting ofmonohydroxyphenyl, dihydroxyphenyl, monohydroxymonomethylphenyl,monohydroxynaphthyl, monochloromonohydroxyphenyl,dichloromonohydroxyphenyl, monobromomonohydroxyphenyl anddibromomonohydroxyphenyl.
 3. A compound according to claim 1, whereinthe (OH)_(m) --Ar² < of the formula (I) is selected from the groupconsisting of monohydroxyphenylene, dihydroxyphenylene,monohydroxymonomethylphenylene, monohydroxynaphthylene,monochloromonohydroxyphenylene, dichloromonohydroxyphenylene,monobromomonhydroxyphenylene and dibromomonohydroxyphenylene.
 4. Acompound according to claim 1, wherein the R¹ and R² of the formula (I)may be same or different and are independently a hydrogen atom ormethyl.
 5. A compound according to claim 1, wherein the q in the formula(I) is a number of 0 to
 5. 6. A process for the production of thecompound of the formula (I) recited in claim 1, which comprisessubjecting to a dehydration and condensation reaction an aldehydecompound of the formula (III) ##STR61## wherein R^(o) is a hydrogen atomor an alkyl group having 1 to 10 carbon atoms and an aromatic hydroxycompound of the formula (IV)

    Ar.sup.o --(OH).sub.u                                      (IV)

wherein Ar^(o) is a benzene skeleton, a naphthalene skeleton or askeleton of the formula ##STR62## in which X is a bond, --O--, --S--,--SO₂, ##STR63## or an alkylidene group having 1 to 3 carbon atoms,provided that these skeletons may be substituted with a halogen atom oran alkyl group having 1 to 5 carbon atoms and that the total number ofcarbons of Ar^(o) is not more than 20, and u is a number of 1 to 3,inthe presence of an acidic catalyst, and optionally, then subjecting thereaction product to a hydrolysis reaction.
 7. An epoxy compound of theformula (II) ##STR64## wherein: Ar¹, Ar² and Ar³ are as defined in theformula (I),G is ##STR65## R³ and R⁴ may be same or different and eachindependently represents ##STR66## or an alkyl group having 1 to 10carbon atoms, p is a number of 0 to 20, and r, s and t are independentlya number of 1 to
 3. 8. A compound according to claim 7, wherein the(OG)_(r) --Ar¹ -- and (OG)_(t) --Ar³ -- of the formula (II) may be sameor different and are independently selected from the group consisting ofmonoglycidyloxyphenyl, di(glycidyloxy)phenyl,monoglycidyloxymonomethylphenyl, monoglycidyloxynaphthyl,monochloromonoglycidyloxyphenyl, dichloromonoglycidyloxyphenyl,monobromomonoglycidyloxyphenyl and dibromomonoglycidyloxyphenyl.
 9. Acompound according to claim 7, wherein the (OG)_(s) --Ar² < is selectedfrom the group consisting of monoglycidyloxyphenylene,di(glycidyloxy)phenylene, monoglycidyloxymonomethylphenylene,monoglycidyloxynaphthylene, monochloromonoglycidyloxyphenylene,dichloromonoglycidyloxyphenylene, monobromomonoglycidyloxyphenylene anddibromomonoglycidyloxyphenylene.
 10. A compound according to claim 7,wherein R³ and R⁴ of the formula (II) may be same or different and areindependently ##STR67## or methyl.
 11. A compound according to claim 7,wherein p in the formula (II) is a number of 0 to
 5. 12. A process forthe production of the epoxy compound of the formula (II) recited inclaim 7, which comprises reacting the compound of the formula (I)recited in claim 1 with a halohydrin selected from epihalohydrins andβ-methylepihalohydrins;(i) at one step in the presence of an basiccompound, or (ii) first in the presence of a quaternary ammonium saltand then in the presence of a basic compound.
 13. A process for theproduction of the compound of the formula (II) which comprises:(1)subjecting a dehydration and condensation reaction an aldehyde compoundof the formula (III)-1, ##STR68## wherein R⁰¹ is an alkyl group having 1to 10 carbon atoms, and an aromatic hydroxy compound of the formula (IV)cited in claim 6 in the presence of an acidic catalyst, (2) subjectingthe resultant reaction mixture to a hydrolysis reaction in the presenceof a basic compound, and (3) adding an halohydrin selected fromepihalohydrins and β-methylepihalohydrins to the resultant hydrolysisreaction mixture to react a hydrolysis reaction product in said mixturewith the halohydrin.
 14. A method of using the compound of the formula(I) ##STR69## wherein: Ar¹, Ar² and Ar³ may be the same or different andeach independently represents a benzene skeleton, a naphthalene skeletonor a skeleton of the formula ##STR70## in which X is a bond, --O--,--S--, --SO₂ --, ##STR71## or alkylidene group having 1 to 3 carbonatoms, provided that these skeletons may be substituted with a halogenatom or an alkyl group having 1 to 5 carbon atoms and that the totalnumber of carbon atoms of each of Ar¹, Ar² and Ar³ is not more than20,R¹ and R² may be the same or different and each independentlyrepresents a hydrogen atom or an alkyl group having 1 to 10 carbonatoms, q is a number of 0 to 20, and each of l, m and n is a number of 1to 3, as a curing agent, comprising adding the compound of formula I toa thermosetting resin to form a cured product.
 15. A molded curedproduct of a thermosetting resin comprising the epoxy compound of theformula (II) ##STR72## wherein: Ar¹, Ar² and Ar³ are as defined in theformula (I), ##STR73## R³ and R⁴ may be the same or different and eachindependently represents ##STR74## or an alkyl group having 1 to 10carbon atoms, p is a number of 0 to 20, andr, s and t are independentlya number of 1 to
 3. 16. A composite material comprising a matrix resinof a cured product of a thermosetting resin comprising the epoxycompound of the formula (II) ##STR75## wherein: Ar¹, Ar² and Ar³ are asdefined in the formula (I), ##STR76## R³ and R⁴ may be the same ordifferent and each independently represents ##STR77## or an alkyl grouphaving 1 to 10 carbon atoms, p is a number of 0 to 20, andr, s and t areindependently a number of 1 to 3, and a reinforcing material.
 17. Acomposite material according to claim 16, wherein the reinforcingmaterial is a carbon fiber, an aramide fiber or a glass fiber.